What diameter should I start with?

[trapperP]

Would like to work up a load combo for the 30/06 and here's what I have: boolits with a nominal weight of 183 grs, powder coated to a diameter of .313 I intend to resize via liquid lube and a push through sizer. Question is what size should I select? Powder, etc no problem as I have a wide variety, just looking to see where to start.

[Wolfer]

I would measure the inside of a fired case. The largest size that will chamber usually works best.

[Jniedbalski]

.311 usually will fit the throat fine. .312 or bigger is hard to close the bolt on my savage

[high standard 40]

I often see a size of .311 suggested but I have a Rem 700 30-06 and it won't chamber a bullet sized over .309". Guns can be and often are very different. I would suggest slugging you chamber. Then you will know what size you need....for you particular rifle.

[largom]

Make a dummy round with the .313 boolit and see if it will chamber with NO resistance. If that does not work then try a .312 boolit and so forth until a round chambers
with NO resistance. Mark the boolits tip with a magic marker to check if they are touching the lands.

[Grmps]

I always start by slugging the barrel then go 1 to 3 thou over depending on the hardness of the alloy and how fast I intend to push the boolit.

[HangFireW8]

Make a dummy round with the .313 boolit and see if it will chamber with NO resistance. If that does not work then try a .312 boolit and so forth until a round chambers
with NO resistance. Mark the boolits tip with a magic marker to check if they are touching the lands.

Always good advice. I do all of this this with the start of reloading cast for every new cartridge, and every new boolit design.

I have to shake my head at the incessant advice here to "go big" with diameter. Phil Sharpe railed against "the rule" of having to go .003" larger than nominal bore (blindly, without slugging)... in the 1930's. In the 50's->60's the NRA did extensive cast bullet testing, and found the best accuracy with rifle bullets cast (but not sized) from 0 (exact match) to .001" over bore size. (I say not sized because sizing negatively effects hardness and concentricity, assuming a really good, well-sized mold).

But some here are obsessed with "ball seat" and "size to throat", which are strategies for oversized old military rifle throats and revolvers. So here you have the end result, a newbie that might not even be able to get his first cast bullet loads to seat in a factory chamber. Be real proud of yourselves, Bro's.

[shredder]

A word of caution: If your cast boolit is tight in a fired case neck, there will be no room for the neck to let go of the boolit in the chamber and extreme pressure excursions can result. Always be sure there is room for expansion of the neck into the chamber. I agree that sized exact to bore or .001 over can give excellent accuracy. There are many ways to skin a cat however and not every rifle responds to that sizing, especially worn military rifles. that is what keeps us interested, the pursuit of accuracy.

[waksupi]

Take a fired case, and put a bullet in. It should have some resistance. If it goes in freely, it is too small. The case will tell you a lot about what fits the throat.

[HABCAN]

What waksupi said: +1.

[Larry Gibson]

In .30 cals .311 is my usual "go to" size diameter. If you can make a chamber or pound cast the bullet should be sized no larger than the diameter of the throat at the chamber mouth.